/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software  Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2017, Blender Foundation
 * This is a new part of Blender
 */

/** \file
 * \ingroup modifiers
 */

#include <stdio.h>

#include "BLI_utildefines.h"

#include "BLI_math.h"

#include "DNA_meshdata_types.h"
#include "DNA_scene_types.h"
#include "DNA_object_types.h"
#include "DNA_gpencil_types.h"
#include "DNA_gpencil_modifier_types.h"
#include "DNA_modifier_types.h"

#include "BKE_action.h"
#include "BKE_colortools.h"
#include "BKE_deform.h"
#include "BKE_gpencil.h"
#include "BKE_gpencil_modifier.h"
#include "BKE_modifier.h"
#include "BKE_library_query.h"
#include "BKE_scene.h"
#include "BKE_main.h"
#include "BKE_layer.h"

#include "MEM_guardedalloc.h"

#include "MOD_gpencil_util.h"
#include "MOD_gpencil_modifiertypes.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_build.h"
#include "DEG_depsgraph_query.h"

/* temp struct to hold data */
struct GPHookData_cb {
  struct CurveMapping *curfalloff;

  char falloff_type;
  float falloff;
  float falloff_sq;
  float fac_orig;

  unsigned int use_falloff : 1;
  unsigned int use_uniform : 1;

  float cent[3];

  float mat_uniform[3][3];
  float mat[4][4];
};

static void initData(GpencilModifierData *md)
{
  HookGpencilModifierData *gpmd = (HookGpencilModifierData *)md;
  gpmd->pass_index = 0;
  gpmd->layername[0] = '\0';
  gpmd->vgname[0] = '\0';
  gpmd->object = NULL;
  gpmd->force = 0.5f;
  gpmd->falloff_type = eGPHook_Falloff_Smooth;
  gpmd->curfalloff = curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
  if (gpmd->curfalloff) {
    curvemapping_initialize(gpmd->curfalloff);
  }
}

static void copyData(const GpencilModifierData *md, GpencilModifierData *target)
{
  HookGpencilModifierData *gmd = (HookGpencilModifierData *)md;
  HookGpencilModifierData *tgmd = (HookGpencilModifierData *)target;

  if (tgmd->curfalloff != NULL) {
    curvemapping_free(tgmd->curfalloff);
    tgmd->curfalloff = NULL;
  }

  BKE_gpencil_modifier_copyData_generic(md, target);

  tgmd->curfalloff = curvemapping_copy(gmd->curfalloff);
}

/* calculate factor of fallof */
static float gp_hook_falloff(const struct GPHookData_cb *tData, const float len_sq)
{
  BLI_assert(tData->falloff_sq);
  if (len_sq > tData->falloff_sq) {
    return 0.0f;
  }
  else if (len_sq > 0.0f) {
    float fac;

    if (tData->falloff_type == eGPHook_Falloff_Const) {
      fac = 1.0f;
      goto finally;
    }
    else if (tData->falloff_type == eGPHook_Falloff_InvSquare) {
      /* avoid sqrt below */
      fac = 1.0f - (len_sq / tData->falloff_sq);
      goto finally;
    }

    fac = 1.0f - (sqrtf(len_sq) / tData->falloff);

    switch (tData->falloff_type) {
      case eGPHook_Falloff_Curve:
        fac = curvemapping_evaluateF(tData->curfalloff, 0, fac);
        break;
      case eGPHook_Falloff_Sharp:
        fac = fac * fac;
        break;
      case eGPHook_Falloff_Smooth:
        fac = 3.0f * fac * fac - 2.0f * fac * fac * fac;
        break;
      case eGPHook_Falloff_Root:
        fac = sqrtf(fac);
        break;
      case eGPHook_Falloff_Linear:
        /* pass */
        break;
      case eGPHook_Falloff_Sphere:
        fac = sqrtf(2 * fac - fac * fac);
        break;
      default:
        break;
    }

  finally:
    return fac * tData->fac_orig;
  }
  else {
    return tData->fac_orig;
  }
}

/* apply point deformation */
static void gp_hook_co_apply(struct GPHookData_cb *tData, float weight, bGPDspoint *pt)
{
  float fac;

  if (tData->use_falloff) {
    float len_sq;

    if (tData->use_uniform) {
      float co_uniform[3];
      mul_v3_m3v3(co_uniform, tData->mat_uniform, &pt->x);
      len_sq = len_squared_v3v3(tData->cent, co_uniform);
    }
    else {
      len_sq = len_squared_v3v3(tData->cent, &pt->x);
    }

    fac = gp_hook_falloff(tData, len_sq);
  }
  else {
    fac = tData->fac_orig;
  }

  if (fac) {
    float co_tmp[3];
    mul_v3_m4v3(co_tmp, tData->mat, &pt->x);
    interp_v3_v3v3(&pt->x, &pt->x, co_tmp, fac * weight);
  }
}

/* deform stroke */
static void deformStroke(GpencilModifierData *md,
                         Depsgraph *UNUSED(depsgraph),
                         Object *ob,
                         bGPDlayer *gpl,
                         bGPDstroke *gps)
{
  HookGpencilModifierData *mmd = (HookGpencilModifierData *)md;
  if (!mmd->object) {
    return;
  }

  const int def_nr = defgroup_name_index(ob, mmd->vgname);

  bPoseChannel *pchan = BKE_pose_channel_find_name(mmd->object->pose, mmd->subtarget);
  float dmat[4][4];
  struct GPHookData_cb tData;

  if (!is_stroke_affected_by_modifier(ob,
                                      mmd->layername,
                                      mmd->pass_index,
                                      mmd->layer_pass,
                                      1,
                                      gpl,
                                      gps,
                                      mmd->flag & GP_HOOK_INVERT_LAYER,
                                      mmd->flag & GP_HOOK_INVERT_PASS,
                                      mmd->flag & GP_HOOK_INVERT_LAYERPASS)) {
    return;
  }

  /* init struct */
  tData.curfalloff = mmd->curfalloff;
  tData.falloff_type = mmd->falloff_type;
  tData.falloff = (mmd->falloff_type == eHook_Falloff_None) ? 0.0f : mmd->falloff;
  tData.falloff_sq = SQUARE(tData.falloff);
  tData.fac_orig = mmd->force;
  tData.use_falloff = (tData.falloff_sq != 0.0f);
  tData.use_uniform = (mmd->flag & GP_HOOK_UNIFORM_SPACE) != 0;

  if (tData.use_uniform) {
    copy_m3_m4(tData.mat_uniform, mmd->parentinv);
    mul_v3_m3v3(tData.cent, tData.mat_uniform, mmd->cent);
  }
  else {
    unit_m3(tData.mat_uniform);
    copy_v3_v3(tData.cent, mmd->cent);
  }

  /* get world-space matrix of target, corrected for the space the verts are in */
  if (mmd->subtarget[0] && pchan) {
    /* bone target if there's a matching pose-channel */
    mul_m4_m4m4(dmat, mmd->object->obmat, pchan->pose_mat);
  }
  else {
    /* just object target */
    copy_m4_m4(dmat, mmd->object->obmat);
  }
  invert_m4_m4(ob->imat, ob->obmat);
  mul_m4_series(tData.mat, ob->imat, dmat, mmd->parentinv);

  /* loop points and apply deform */
  for (int i = 0; i < gps->totpoints; i++) {
    bGPDspoint *pt = &gps->points[i];
    MDeformVert *dvert = gps->dvert != NULL ? &gps->dvert[i] : NULL;

    /* verify vertex group */
    const float weight = get_modifier_point_weight(
        dvert, (mmd->flag & GP_HOOK_INVERT_VGROUP) != 0, def_nr);
    if (weight < 0.0f) {
      continue;
    }
    gp_hook_co_apply(&tData, weight, pt);
  }
}

/* FIXME: Ideally we be doing this on a copy of the main depsgraph
 * (i.e. one where we don't have to worry about restoring state)
 */
static void bakeModifier(Main *bmain, Depsgraph *depsgraph, GpencilModifierData *md, Object *ob)
{
  HookGpencilModifierData *mmd = (HookGpencilModifierData *)md;
  Scene *scene = DEG_get_evaluated_scene(depsgraph);
  bGPdata *gpd = ob->data;
  int oldframe = (int)DEG_get_ctime(depsgraph);

  if (mmd->object == NULL) {
    return;
  }

  for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
    for (bGPDframe *gpf = gpl->frames.first; gpf; gpf = gpf->next) {
      /* apply hook effects on this frame
       * NOTE: this assumes that we don't want hook animation on non-keyframed frames
       */
      CFRA = gpf->framenum;
      BKE_scene_graph_update_for_newframe(depsgraph, bmain);

      /* compute hook effects on this frame */
      for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
        deformStroke(md, depsgraph, ob, gpl, gps);
      }
    }
  }

  /* return frame state and DB to original state */
  CFRA = oldframe;
  BKE_scene_graph_update_for_newframe(depsgraph, bmain);
}

static void freeData(GpencilModifierData *md)
{
  HookGpencilModifierData *mmd = (HookGpencilModifierData *)md;

  if (mmd->curfalloff) {
    curvemapping_free(mmd->curfalloff);
  }
}

static bool isDisabled(GpencilModifierData *md, int UNUSED(userRenderParams))
{
  HookGpencilModifierData *mmd = (HookGpencilModifierData *)md;

  return !mmd->object;
}

static void updateDepsgraph(GpencilModifierData *md, const ModifierUpdateDepsgraphContext *ctx)
{
  HookGpencilModifierData *lmd = (HookGpencilModifierData *)md;
  if (lmd->object != NULL) {
    DEG_add_object_relation(ctx->node, lmd->object, DEG_OB_COMP_GEOMETRY, "Hook Modifier");
    DEG_add_object_relation(ctx->node, lmd->object, DEG_OB_COMP_TRANSFORM, "Hook Modifier");
  }
  DEG_add_object_relation(ctx->node, ctx->object, DEG_OB_COMP_TRANSFORM, "Hook Modifier");
}

static void foreachObjectLink(GpencilModifierData *md,
                              Object *ob,
                              ObjectWalkFunc walk,
                              void *userData)
{
  HookGpencilModifierData *mmd = (HookGpencilModifierData *)md;

  walk(userData, ob, &mmd->object, IDWALK_CB_NOP);
}

GpencilModifierTypeInfo modifierType_Gpencil_Hook = {
    /* name */ "Hook",
    /* structName */ "HookGpencilModifierData",
    /* structSize */ sizeof(HookGpencilModifierData),
    /* type */ eGpencilModifierTypeType_Gpencil,
    /* flags */ eGpencilModifierTypeFlag_SupportsEditmode,

    /* copyData */ copyData,

    /* deformStroke */ deformStroke,
    /* generateStrokes */ NULL,
    /* bakeModifier */ bakeModifier,
    /* remapTime */ NULL,

    /* initData */ initData,
    /* freeData */ freeData,
    /* isDisabled */ isDisabled,
    /* updateDepsgraph */ updateDepsgraph,
    /* dependsOnTime */ NULL,
    /* foreachObjectLink */ foreachObjectLink,
    /* foreachIDLink */ NULL,
    /* foreachTexLink */ NULL,
    /* getDuplicationFactor */ NULL,
};
